Lug Lapping Tool

[Tim Oltersdorf]

I need some information and advice from you gentlemen. I want to purchase a tool that would screw into the barrel threads of an action and exert spring pressure on the bolt face. This would be used when lapping the bolt lugs. I have a couple of questions:
1 Does anyone market this tool for a 18 TPI BR action?
2 If necessary I could make it on my lathe. What would you use for the material that presses on the bolt face? Where should I press on the bolt, bolt face or cone?
3 What do you think of the wisdom of using this tool for minor lug lapping? (Feel free to question my intelligence, physical appearance, common sense and sexual orientation. My wife does daily.) Thanks. Tim

 

[C.L. Peterson]

I need some information and advice from you gentlemen. I want to purchase a tool that would screw into the barrel threads of an action and exert spring pressure on the bolt face. This would be used when lapping the bolt lugs. I have a couple of questions:
1 Does anyone market this tool for a 18 TPI BR action?
2 If necessary I could make it on my lathe. What would you use for the material that presses on the bolt face? Where should I press on the bolt, bolt face or cone?
3 What do you think of the wisdom of using this tool for minor lug lapping? (Feel free to question my intelligence, physical appearance, common sense and sexual orientation. My wife does daily.) Thanks. Tim

Tim
"Brownells" sells a bolt lapping set/kit/tool
I would look to see if that will fit your project.
Also one could call them to make sure you get the right tool
Good Luck
CLP

 

[Zebra13]

Tim,

If you got a lathe, make it yourself...not hard to do. It's about a 30 minute project. I made mine out of aluminum, with the "pusher" being brass, IIRC, and pushing on the bolt face. I think I drilled a hole in the bottom of the pusher a bit bigger than the firing pin hole so as to avoid the firing pin hole shearing material off of the pusher. If I did it over again, I'd tip the pusher with a phenolic of some sort...Teflon, delrin, UHMW, etc.

Use it sparingly...my understanding is that too much lapping will induce an angle on the locking lug recesses due to their leading edge area being in constant contact with a bolt lug. It seems the bolt lugs would suffer the same angled fate. I guess it would depend on which one is harder. I'd use some Prussian blue on the lugs and recesses to check the contact before I went after them with a lapping tool.

I think most around here use it to knock off the high spots/tooling marks on the lug recesses/locking lugs following an action trueing...if they use it at all. I don't use mine. Grind your cutting tools right and you get a nice surface finish on both surfaces.

Hope it helps,
Justin

PS: Despite what I hear about you having an attraction to cross-dressing midgets wearing powdered wigs, I would never question your sexual orientation...

 

[Fussy1]

OP, I have never used a lapping tool. Nevertheless, I vote for a non-springloaded version, if available.
F1

 

[MilGunsmith]

Build one yourself. Good practice for threading a barrel. You can also cut the tenon off of an old barrel and use that for the body. Make the pusher out of brass or delrin.

 

[Dave Tooley]

I built mine spring loaded but I always fully compress the spring and tighten to adjust pressure as the lapping compound breaks down.

 

[Tim Oltersdorf]

Thanks

Thank for all the great advice. I have found several of these tools for sale but all are for 16 tpi or Mauser actions. I have found no 18 tpi ones. I will make myself one after Christmas. By the way Zebra 13, how did you find out about the midgets? Tim

 

[jackie schmidt]

Thank for all the great advice. I have found several of these tools for sale but all are for 16 tpi or Mauser actions. I have found no 18 tpi ones. I will make myself one after Christmas. By the way Zebra 13, how did you find out about the midgets? Tim

Tim, maybe the consensus is any action with an 18 thread per inch tenon is a custom action and should not need lapping.

They are easy to make. I made one years ago when we fooled with Remington Actions a lot.


http://benchrest.com/attachment.php?attachmentid=18737&stc=1&d=1481819036

http://benchrest.com/attachment.php?attachmentid=18738&stc=1&d=1481819152

 

[Fussy1]

Justin, a BTW re angled lugs; I think that BSA/HertersU9s have pre-angled lugs. And SMLES, too?
F1

 

[Zebra13]

Justin, a BTW re angled lugs; I think that BSA/HertersU9s have pre-angled lugs. And SMLES, too?
F1

Fussy1,

I haven't the foggiest idea...

If they do, why? Maybe to induce a camming action to ensure the round chambers? I could see that being advantageous on a battle rifle like the SMLE.

Justin

 

[John Kielly]

If they do, why? Maybe to induce a camming action to ensure the round chambers? I could see that being advantageous on a battle rifle like the SMLE.

I think most rifles of that vintage had a degree of angling to their lugs, and considering tolerances of the day, I suspect that you might be correct.

 

[alinwa]

I think most rifles of that vintage had a degree of angling to their lugs, and considering tolerances of the day, I suspect that you might be correct.

Seems a crazy difficult machining process, several extra steps required for a wartime rifle......what am I missing?

 

[Fussy1]

I'm scratching my head, wondering if the angled lugs would aid extraction. ?
F1

 

[alinwa]

I'm scratching my head, wondering if the angled lugs would aid extraction. ?
F1

No

 

[Fussy1]

I suspect that you're right. There may have been something about it in de Haas' Bolt Action book, but I have misplaced mine.
F1

 

[jackie schmidt]

I suspect that you're right. There may have been something about it in de Haas' Bolt Action book, but I have misplaced mine.
F1

I am not familiar with how much lead angle was put on the locking lugs of old military bolt action Rifles, but if the do indeed incorporate this feature, it was probably done to facilitate chambering in less than ideal conditions, i.e., mud, sand, dirt, that could find its way into the bolt way.